Abstract : The 3-in./70 Caliber Mount Mark 28 Mod 0 is a prototype of the Mark 37 production mounts which will be undergoing tests at the Naval Proving Ground within six (6) months to a year. The Mark 37 mounts are twin installations capable of firing at the cyclic rate of 90 rounds per minute per barrel, whereas the Mark 28 mount is composed of one-half of a twin installation; that is, only one gun and ammunition handling system is provided. The purpose of these tests of the Mark 28 mount was to obtain information relative to the reliability of the ammunition handling system, and to obtain numerous miscellaneous data relative to the performance of the mount and certain associated equipment.